Syntheses of 3,4-ethylenedioxythiophene-based vinylenes and oligomers are reported.

A series of mixed thiophene/furan oligomers have been synthesized via organometallic Stille coupling. In some cases, beside cross-coupling products, symmetrical coupling products were isolated. Oligomers consisting of up to 11 rings were obtained. Attempts to prepare macrocycles with 10 thiophene and furan units were not successful.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

1,1-Dioxo-1,2-thiazine-6-carbaldehydes 1 possessing a masked 1,5-dicarbonyl structure react with hydroxylamine with ring transformation to form the pyridine N-oxides 2. These can be deoxygenated with PCl3 to give the corresponding pyridine-3-sulfonanilides 3, which are available by the reaction of 1 with ammonia as well. The ring transformation of 1 with methylamine, benzylamine and hydrazine produces N-substituted mesoionic pyridinium salts 6-8. The cyclohexane-fused thiazine-6-carbaldehyde 9 can be transformed with ammonia to the 5,6,7,8-tetrahydoquinoline 10. Reaction of 2 with NaNO2/HCl enables the introduction of the nitro group into the anilide part of the molecule.

The formylation of 2-aryl-3,5-dimethyl-1,1-dioxo-1,2-thiazines with POCl3/DMF leads to the thiazine-6-aldehydes 1 and to the bis-vinamidinium salts 2. The reaction of 2a,b with hydroxylamine results in the formation of the pyrido-thiazine-N-oxides 5a,b, which give with PCl3 the 5-cyano-3-isoxazol-4-yl-pyrido[4,3-e]thiazines 6a,b. The pyrido-thiazines 9a and 10a are obtained by base-induced opening of the isoxazolyl-ring in 5a and 7a to the cyanoformylmethyl group. The compounds 6a and 7a were characterized by Xray structure analysis.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis and Characterization of Stilbazolium Dyes with Mesoionic 1,2-Diazinium Structure Pyridazinium salts of typ 1 react with substituted aromatic and heteroaromatic aldehydes 2a, e–h, 8a–c and trans-p-dimethylamino-cinnamaldehyde 3a to the charge transfer dyes 4a–h, 5a–d, 9a–c. They absorb in the range between 380 and 660°nm. The dehydratisation of the aldoxime group in 4, 5 to the nitril group under formation of 6, 7a–d causes a bathochromic shift of the absorption band up to 110 nm. The UV-VIS data are discussed dependent on the structure of the dyes.

The thiazines 1b-e, g, h react with isoamyl nitrite/HClg by nitrosation of the 3-methyl group to the 3-cyano-thiazines 3b-e, g, h. As by-products the mesoionic pyridazinium salts 4b, c are formed. The compounds 4b-i and 4-1e-i became main products by the nitrosation of 1b-i with sodium nitrite/HCl. In this case as by-products the oximes 2b-d were isolated, which can be transferred with sodium nitrite into 4b-d, The regioselectivity of the nitrosation reaction of 1 is influenced by the substituents of the aryl group.